Strip stock feeding system for punch press



May 19, 1970 J. T. BURDGE 3,512,438

STRIP STOCK FEEDING SYSTEM FOR PUNCH PRESS Filed Dec. 11, 1967 141: L W.I- E

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47- TaQNEV United States Patent 3,512,438- STRE STOCK FEEDIrNlgESSSYSTEMFOR PUNCH James T. Burdge, Panorama City, Calif., assignor of onehalf toDoron Plastics, Inc., Monterey Park, Califl, a corporation of CaliforniaFiled Dec. 11, 1967, Ser. No. 689,674 Int. Cl. B2611 5/22 US. Cl. 832091 Claim ABSTRACT OF THE DISCLOSURE An outfeed system is provided forstrip stock in a punch press. It is coordinated with a conventionalinfeed system, and affords a continuously operating punching system ofhigh production rate having, on the infeed side of the press, an airpowered reciprocating feed clamp for intermittently clamping andadvancing the strip stock through a fixed distance, a stationary stockclamp on the infeed side of the press for clamping the strip stockalternately with the infeed clamp, in order to hold the stock steady forpunching, and has, an addition, on the outfeed side of the punch press,a similar pair of feeding and stock or holding clamps for feeding thestrip stock mechanically all of the way through the punch press, and atthe same time permitting the strip stock to be punched for its entirelength. The outfeed system permits automatic feed of successive strips,punching of each strip from end to end with mechanical indexing to andbeyond the trailing end of each strip.

FIELD OF THE INVENTION This invention relates generally to feed devicesfor feeding lengths of plastic strip stock or the like through a punchpress, wherein the strips are advanced step by step, and punched in apredetermined pattern at a punching station during each stop interval.

The strip stock may be flat, or have various crosssectional forms. Inthe present example, the strip stock is angular in cross section,comprising two flat flanges joined at an angle of 90, with both flangesto be punched. The material in this case should be somewhat flexible,particularly at the junction of the flanges, to permit the latter to bespread to a larger and more convenient angle during the punchingoperation.

BACKGROUND In the past, commonly known power punch infeeds have beenavailable for feeding flat strip stock into a punch press. Such devicesare manufactured by Mechani cal Tool & Engineering Company, of Rockford,Ill., designated as Type 2, and make use of such punch press feeds as abasic component. With such feeds, however, there has been no feasibleway known for mechanically feeding each successive strip all the waythrough the press. It has either been manually pulled from the machine,with measured stops (after passing beyond the infeed) to permit and tospace successive punch strokes; or else attempts have been made to pushthe strip through by oncoming or next succeeding strip as the latter isadvanced by the infeed. The infeed in these prior machines acts on theincoming strip through two normally open automatically actuated clamps.These include, first, an intermittently acting feed clamp which clampsthe strip, then advances it towards the punch press by a predeterminedindexing distance, and then releases it and returns to its initialposition. Second, there is a holding or so-called stock clamp whichclamps the strip rigidly during the time interval occurring betweenintermittent clamping engagements of the strip by the infeed clamp. Thestrip is held rigidly by this stock clamp during the punching operation.The cycle is then repeated. Both clamps in this system are on theingoing side of the punch press, as earlier intimated. It will be seenthat as the trailing end of the strip passes beyond the first mentionedclamp, i.e., the intermittently acting infeed clamp, there is nothingwithin the machine to continue the advance of the strip. It can ofcourse be pulled step-by-step through and then out of the punch press byhand, between clampings by the stock clamp, and then after the stockclamp has been passed. Alternatively, and as sometimes attempted, afollowing strip has been fed in immediately behind each strip, andrelied on to shove the preceding strip on through after the latter haspassed beyond the reach of the infeed. However, in practice, thisprocedure did not work with satisfaction in all cases, since the stripssometimes became overlapped with one another, thereby jamming theoperation. A satisfactory solution for this problem has not heretoforebeen available to my knowledge.

SUMMARY OF THE INVENTION In accordance with the present invention, Iprovide additionally a second set of normally open feed and stock clampslocated on the outgoing side of the punch press. The first of theseencountered by a strip emerged from the punch press is an outfeed clampwhich intermittently engages the strip and clamps it, then advances itthrough the predetermined indexing distance, then releases it, andreturns to its initial position; and the second is a stock clamp,coordinated with the added outfeed clamp. The infeed clamp at theingoing side of the punch press feeds the strip far enough to comewithin the range of the added outfeed clamp at the outgoing side of thepunch press. The outfeed clamp at the outgoing side of the punch pressthereupon intermittently engages the strip and feeds it forwardly by theindexing distance. The added stock clamp at the outgoing end of thepunch press receives the strip before or by the time the strip has leftthe position of the stock clamp at the ingoing end of the punch press.Accordingly, as the strip is further punched and advanced, it isintermittently clamped by the stock clamp at the outgoing side of thepress. Thus, a strip of material to be punched is moved automatically,in a succession of steps, entirely through the punch press, and can bepunched continuously along its full length by a machine controlledindexing distance. Moreover, the strip passes automatical- 1y throughthe entire machine, and can be removed by hand or by other means as itemerges, fully punched, from the apparatus.

DESCRIPTION OF FIGURES The invention will be further understood from thefollowing detailed description taken in connection with the accompanyingdrawings showing an illustrative embodiment of the invention, and inwhich:

FIG. 1 is a largely diagrammatic side elevational view of a punch pressequipped with the improvements of the present invention;

FIG. 2 is a section taken on line 22 of FIG. 1;

FIG. 3 is a section taken in accordance with line 33 on FIG. 1;

FIG. 4 is a diagrammatic view showing a position in the operation of thefeeding equipment of the invention corresponding to FIG. 1;

FIG. 5 is a view similar to FIG. 4 but showing a subsequent position;and

FIG. 6 is a fragmentary perspective view of strip stock of angular crosssection punched with illustrative dia- 3 mond shaped slots in accordancewith the machine and process of the invention.

DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT Referring now to FIG. 1, aconventional punch press is designated generally by the numeral 10. Thispunch press has two laterally spaced standards 11, understood normallyto rise from the floor, and in the upper ends of these standards isjournalled a shaft 12 driven by a schematically designated motor M,reduction gear R, and one-to-one ratio transmission meansdiagrammatically indicated at T (FIG. 1). Shaft 12 carries a fly wheel13, and has between standards 11 an eccentric 14 which works in ahorizontally elongated slot 15 in a cross head 16. The latter is on theend of a vertically reciprocating connecting rod 17, constrained bymeans not shown for vertical travel, and on the lower end of shaft 17 isa cross head 18 bearing, on its underside, a pair of sequential punches19 spaced apart as shown. On the undersides of the punches 19 are punchelements (not shown) of any kind desired and which in this case may beassumed to be diamond shaped, to punch diamond shaped slots and as seenin FIG. 6. The nature of the punch elements is not germane to thepresent invention and need not be detailed. For present purposes theelements 19 may be regarded as punches, bearing on the bottoms thereofpunch elements (not shown) designed to punch openings in any patternthat may be desired in any give case. Below the punches 19, and mountedon a table generally designated at T, are die-blocks 20 having dieopenings, not shown, corresponding to the pattern of punch elements onthe undersides of the punches 19.

A feature of the punch press is that each successive area of each stripS of stock is punched twice, once by the punch elements on punch 19throughout an elongated area equal in length to the indexing distance D,and subsequently, after two steps forward, by intervening punch elementsnecessary to be forced through the stock on each punching stroke is thushalved, to obvious advantage.

At three positions, in between the punches 19, just ahead of the firstpunch 19, and just beyond the second punch 19, are pairs of guides 24and guide rollers 25, shaped to spread the present illustrative normally90 angle stock strips S as this stock moves over the guide and under therollers. The stock is punched in this position by the punches 19. Asseen in FIG. 2, the rollers 25 and the guide 24 are mounted suitably onthe table T.

A length L of said stock is seen in the punch press, within butunclamped by the first or infeed clamp C1 and just short of outfeedclamp C2). Another length L, already punched from end to end, is shownas clamped by normally open stock clamp C2s, and is about to be releasedthereby, and clamped by outfeed clamp C2 In the present embodiment ofthe invention, the strip stock S (here of angle section) is fed in fromthe right, as seen in FIG. 1, and passes sequentially through anintermittent infeed clamp C11, then through a stock clamp Cls on theinfeed side, adapted to grip the stock for punching betweenadvancements, then through the punch area, and thereafter through anintermittent outfeed clamp G2 on the outfeed side, and finally throughan outfeed stock clamp 02s.

FIG. 3 is a sectional view through a clamp, and is generallyrepresentative of either a feed clamp or a stock clamp, on either theinfeed or outfeed sides of the punch, an outfeed clamp beingspecifically shown in this case. A base or housing above table T has atthe top a clamp plate 31, of the same obtuse angle shape as theaforementioned guide 24, and accordingly, conforms to the angle-shapedstock S when the latter is spread to its obtuse angle punching position.Over the plate 31 is a movable clamp plate 33, of the same obtuse-angleconformation, and the ends of this clamp member 33 are bored to passpiston rods 35 extending down into where there are pneumatic pistondevices, not shown because of their conventional nature, for pullingthem down at predetermined times in the operating cycle. Coil springs 36surround the rods 35 between the clamp plate 33 and the base 30, andthus bias the clamp normally to open position. The upper portions of therods, above the member 33, are here shown as screw-threaded, andfurnished with nuts 38 to set the clamps in adjusted positions. When thestock S is to be clamped, air valve and piston devices within the base30 of a character well known in the aforementioned Rapidair feed,operate to move the pins 35 and clamp plate 33 downwardly to clamp thestock (not shown in FIG. 3) downward against the angular plate 31.Assuming the clamp to be a stock clamp, the stock is thereby clampedwhile being punched, and is subsequently released by upward movement ofthe rods 35 under the influence of the bias springs. Assuming the clampshown in FIG. 2 to be representative of a feed clamp, the stock is firstclamped by downward move ment of the rods 35 and plate 33, is thenadvanced, as from the position shown in FIG. 1 through the indexingdistance D, whereafter the rods 35 rise to unclamp the stock, under theinfluence of the bias springs, and the clamp returns to the positionshown in FIG. 1. These movements are determined and controlledautomatically by well known devices contained within the clamp bases,these being designated generally at 30 for the clamp bases under thefeed clamps, and at 31 for the bases under the stock clamps. Controldevices for operating the feed and stock clamps at the ingoing side ofthe machine are known in the Rapidair machine described hereinabove, andneed not be detailed herein as they now may be regarded as conventional.Corresponding components are provided for the stock and feed clamps onthe outgoing side of the machine, but these are controlled andsynchronized with the first-mentioned feed and stock clamps to give aunique overall performance, with an increase in production rate of theorder of a thousand times.

The base members 30 of the feed clamps travel as reciprocating slideblocks which slide in suitable ways, afforded as by rails 30a understoodto extend from the stationary base members 31 towards and from the basemembers 31. A piston or plunger 38 inside each of the members 31 isconnected by a connecting rod such as 40 to the base member or slideblock 30. The piston 38 under suitable control from pneumatic air flowmeans and valving, comprise the means for reciprocating the feed clampsthrough the paths described, and for an understanding of the details ofthis mechanism, reference is directed to the conventional and commercialRapidair feed now well known in the art, and requiring no furtherdescription in this specification.

Leaving control and synchronizing equipment for description until later,and assuming two strips or lengths L and L' of stock S to be in thepunch press in the successive positions shown in FIG. 1 (see also FIG.4), the

sequence of operations is as follows: In the present embodiment of theinvention, the stock is fed in from the right. The clamps are biasednormally open to permit this. With reference first to FIGS. 1 and 4, themachine is shown in a selected position of the operating cycle with thestock clamp Cls closed in clamping position on L and with the infeedclamp C1 open, and retracted to its rightward or beginning position. Atthis same time, outfeed clamp C27 is in open position and retracted,while stock clamp C2s is closed on L. The two pairs of stock and feedclamps operate synchronously with one another. The eccentric, push rod17, and punches are down in the position of FIG. 1 at the completion ofa punching stroke.

Feed clamps C1 and C2 next close and clamp the stock strips L and L,while stock clamps Cls and C2s open. Eccentric 14 elevates the punches,so the strips can be advanced. Base members 30 on both sides of thepress, together with their respective feed clamps Clf and the strips Land L' clamped thereby, are then advanced the indexing distance D, as tothe position of FIG. 5, at which time feed clamps C19 and CM, open, byelevation of their piston rods 35, with the biasing influence of springs36, and stock clamps Cls and C2s close, by lowering of the correspondingpiston rods 35, to hold the stock firmly and stationarily. The infeedand outfeed clamps return to the initial open position of FIG. 1. Thepunching stroke occurs at this time, as the eccentric 14 moves down.Stock clamp 02s at this moment is clamping already punched strip lengthL and is about to release it, while outfeed clamp 02 is about to clampit and then advance it the indexing distance D. Concurrently, the partsbeing still in the position of FIG. 1, stock clamp C19 is clampingpartially punched strip length L, and is about to release it, while feedclamp Clf is about to clamp length L and then advance it the indexingdistance D.

As explained earlier, the two punches U have intervening punch elementsso that half the pattern is punched by the first punch, and theremainder by the second. It will also be easily seen that a given areaof the punch, equal to distance D, is first punched by the first punch19; in the second punch stroke, this area is between the two punches;and on the third punch stroke, the given area is punched in interveninglocations by the punch elements of the second punch 19.

of the operation to shove the strip L' ahead of it, until the 3 latteris removed by hand or otherwise. As the strip L advances intermittentlybeyond the position where it is first clamped by the outfeed clamp C21,it finally passes beyond the location of infeed side stock clamp Cls;and, thereafter, the outfeed side stock clamp C2s intermittently gripsthe strip L to hold it steady while being punched.

Successive strips are thus passed intermittently through the machine,punched in a continuous pattern, and delivered from the machine, in acontinuous operation, which can take place reliably at a higher order ofspeed and uniformity than has heretofore been known.

Suitable control equipment will next be described.

Incoming air under pressure is delivered via pipe 50 to hand valve 51,and beyond the latter, goes to an air valve 52 opened by energization ofa control system solenoid housed therewithin. Beyond valve 52, an airpipe 54 goes to a pneumatically operated solenoid-controlled valvesystem for operating the infeed clamp 01 and stock clamp Cls. This airpipe or line 54 is here shown as connected to base or housing 31, andthe air flow is under the control of a solenoid 56. Momentaryenergization of this solenoid 56 results in valve-controlled air flowswhich cause the stock clamp Cls and infeed clamp Clf to automatically gothrough one cycle of the infeed events as described earlier. Asmentioned earlier, this pneumatic system is known in the art, and issold under the trademark Rapidair. Only a portion of its parts aretherefore here indicated. It may be mentioned that air for operation oftheinfeed clamp passes from housing 31 to pneumatic devices in housing30 via an air passage 58 in plunger 40 (FIG. 3). It is a characteristicof this system that the clamps always come to rest normally in the upposition, the bias springs 36 serving this function. The energization ofthe solenoid, which starts operation of the infeed mechanism, will bedescribed presently.

The outfeed and stock clamps C2 and (32s, added by the presentinvention, are powered pneumatically by air via a line 70, taking olfbetween valves 51 and 52, and thus not under control of the solenoidvalve 52 which controls the air to the clamps C1 and Cls on the infeedside. This line 70 goes to the stationary base, 31 on the outfeed sideof the press, and is under the control of a solenoid 56a, correspondingto the solenoid 56. Thus, with air valve 51 open, the energized solenoid56a results in valve-controlled air flows which cause the stock clampC2s and outfeed clamp GM to undergo one cycle of the events for theseclamps as described earlier.

The energization of the solenoids 56 and 56a at proper times isaccomplished as follows: The output drive shaft 80 from the reductiongear R carries a cam 81 which periodically, once each revolution of thepress drive shaft 12, closes a microswitch M. Thereby, an electriccircuit 84 is closed from a source of potential 85, through themicroswitch M, and through both solenoids 56 and 56a, in parallel, toground. If the punch press is in operation, this circuit closure willcause the outfeed clamps C2 and C2s to undergo their previouslydescribed cycle of events repeatedly, being restarted each time themicroswitch M is energized by the cam 82.

The infeed clamps C1 and C2s will not be started, however, withoutanother condition being fulfilled, namely, the presence of strip stockin the press. A microswitch SM supported on table T at the infeed sideof the press is engaged by the end of an incoming strip of stock S andmoved to close the circuit 88 that energizes the solenoid of the valve52, thus feeding air through said valve to the pneumatic valve system inthe infeed side base 31. This microswitch is held closed by the stripstock until the latter passes said switch, at which time the clamps Clfand C2s are deactivated, and come to rest in open position. The strip isthen, however, within the reach of the outfeed clamps C21 and C2s, whichtake the strip on through.

The completely mechanized feeding system of the invention tremendouslymultiplies the capacity and output of the punch press, as should beobvious.

A strip product presently being punched in accordance with the inventionis shown in FIG. :6. Many other crosssectional shapes and slot shapesmay of course be devised and equally well used in the practice of theinvention.

What is claimed is:

1. In a system for feeding lengths of strip stock through a punch presshaving reciprocating punch means and infeed and outfeed sides, and stripguide elements defining a rectilinear path for said strip from saidinfeed side to said outfeed side including an infeed portion in advanceof said punch means, a punching station portion extending to and pastsaid punch means, and an outfeed portion beyond said intermediateportion, the combination of:

a normally open feed clamp and a normally open stock clamp positioned inseries along said infeed portion of said path; normally open feed clampand a normally open stock clamp positioned in series along said outfeedportion of said path, the feed clamp and stock clamp on each of theinfeed and outfeed portions of said path being cooper-able in anoperating cycle whereinthe said feed clamp, from an open startingposition, clamps strip stock extending therethrough, advances along saidpath to feed said stock a predetermined distance, unclamps said stock,and returns to said starting position, and said stock clamp clamps saidstock during the interval in which said feed clamp is unclamped fromsaid strip stock; means timed by the reciprocating punch forsynchronizing the operating cycles of the outfeed feed and stock clampswith the infeed feed and stock clamps, all in such manner that a lengthof strip stock introduced along said path is first intermittentlyadvanced by said infeed clamp, and alternately therewith clamped by saidinfeed stock clamp, is subsequently intermittently advanced by theoutfeed clamp, and alternately therewith clamped by said infeed stockclamp, and is thereafter intermittently ad- 7 vanced by said outfeedclamp, and alternately therewith clamped by said outfeed stock clamp;

a pneumatic system for powering the clamping and strip feeding events ofsaid operating cycles of said clamps; and

control means for said pneumatic system including means initiatingcyclic operation of the infeed clamp and infeed stock clamp when stripstock in said infeed portion of said path has advanced to apredetermined point relative to said punching station, and alsoincluding means for initiating cyclic operation of the outfeed clamp andoutfeed stock clamp irrespective of presence of strip stock at any pointalong said guide path.

References Cited UNITED STATES PATENTS 2,359,140 9/ 1944 Meitner 83277 X2,961,138 11/1960 Kaye 83--277' X 3,123,270 3/1964 Olson 226 -162 X3,125,270 3/ 1964 Ronfeldt Y 226162 X RICHARD A. SCHACHER, PrimaryExaminer US. Cl. X.R.

